Which of the following is least likely to be part of a cell membrane?Group of answer choicesphospholipidstransport proteinsproteoglycansglycoproteins

The least likely to be part of a cell membrane is proteoglycans.

Here's why:

1. Phospholipids: These are the primary and most crucial components of the cell membrane. They form the basic structure of a cell membrane, known as the lipid bilayer.

2. Transport Proteins: These are integral membrane proteins that help move substances across the cell membrane. They are essential for the functioning of the cell.

3. Glycoproteins: These are proteins that have oligosaccharides (chains of sugars) attached to them. They are found in the cell membrane and play a role in cell-cell interactions and recognition.

4. Proteoglycans: These are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). Proteoglycans are found mainly in the extracellular matrix, not in the cell membrane. They fill up spaces between cells and bind cells with the extracellular matrix. They are less likely to be found in the cell membrane compared to the other components listed.